170 likes | 276 Views
Diamond Sensor Tests for the CMS BCM. Alexandr Ignatenko. FCAL collaboration meeting May 7, 2008. Overview. BRM system overview Standard set of measurements in Zeuthen Thickness Capacitance I-V characteristic Charge collection distance Results Usual behavior Abnormal cases
E N D
Diamond Sensor Tests for the CMS BCM AlexandrIgnatenko FCAL collaboration meeting May 7, 2008
Overview BRM system overview Standard set of measurements in Zeuthen Thickness Capacitance I-V characteristic Charge collection distance Results Usual behavior Abnormal cases Conclusion FCAL collaboration meeting 2
The components: FCAL collaboration meeting
BCM2+BSC2, 14.4m BCM1, 1.8m FCAL collaboration meeting
Thickness and capacitance measurements Thickness: mechanically with 10 µm precision Values 400-430 µm A sensor assembled in the frame Capacitance: with LCR meter HP 4263A 10.7-12.1 pF FCAL collaboration meeting 5
I-V characteristic N2 atmosphere 0-500-0 V 50V/30 sec steps Voltage source and picoamperemeter: Keithley 487 FCAL collaboration meeting
Charge collection distance (CCD) Detection mechanism traps Charge collection efficiency = Qmeas/Qind Charge collection distance CCD = × d FCAL collaboration meeting
CCD setup FCAL collaboration meeting
~ CCD Typical spectrum CCD = (Mean-Ped)×calib×corr/Nexp CCD = (MPV-Ped)*calib/Nexp FCAL collaboration meeting 9
CCD setup Source holder with collimator HV supply and picoampearmeter Sensor box Trigger box Low voltage power supply FCAL collaboration meeting 10
Normal behavior Results depumped P28 pumped negative positive FCAL collaboration meeting
CCD vs dose, pumping CCD dependence on dose, irradiation @ 0.7 Gy/h irradiation started The current in the sensor circuit was monitored FCAL collaboration meeting 12
CCD dependence on time for the fully pumped sensors After additional 60 mGy The current in the sensor circuit was monitored 200 V applied 400 V applied 13 FCAL collaboration meeting
Abnormal cases P18 Depumped state Pumped state Currents up to hundreds of nA at high bias voltages FCAL collaboration meeting
depumped P 45 pumped FCAL collaboration meeting
Currents had changed in time even without irradiation FCAL collaboration meeting 16
Conclusion • 25 samples have been investigated • The characterization of each sample has been given • 6 sensors have shown unstable • currents • The parameters of the sensor were reproducible FCAL collaboration meeting 17